The SixSixOne Summit MIPS Helmet is a tech packed, modern trail helmet featuring MIPS, Contego EPS foam and a Fidlock magnetic buckle.MIPS (Multi-directional Impact Protection System)Light and well-ventilated design through in-moulded construction with 15 ventsAdditional protection through extended rear shell coveragePrecise fit for all with 3 shell sizePlush interior liner made with antimicrobial fabricContego EPS materialFidlock closure systemMIPS Technology works to reduce the 'rotational violence' transmitted to the rider's brain during an angular impact, by using a low-density liner (LDL) between the EPS foam and liner pads. Contego EPS foam is used for its ability to absorb and dissipate more impact force than a conventional EPS foam. The Magnetic Fidlock closure system is in place to aid the ease of one-handed buckle operation.Size Guide:X-Small/Small - 52-56cmMedium/Large - 57-59cmX-Large/XX-Large - 60-62cm